Safety guard for interrupted cylinders



Jan. 9,` 1945.V w. J. `F'IRIE SAFETY GUARD FOR ITERRUPTED CYLINDERS Eed Feb. 5, 1944 5 Sheets-Sheet 1 Jan. 9, 1945. w. J. PIRIE A SAFETY GUARD FOR INTERRUPTED CYLINDERS ajo Jan. 9, 1945. w. J. PIRIE SAFETY GUARD FOR INTERRUPTED CYLINDERS" 3 Sheets-Sheet 3 Filed Feb. 5, 1944 Patented Jan. 9, 1945 @9X1 1 He@ ofir tu the prlntingplate,

vicenormany ompltly clqsingtheV gap 'in me afa.. el

@ela di., th

ing cylinder illustrating one gap guard closed' and the other open.

Fig. 2 is a fragmentary sectional elevational view of the cylinder showing the gap guard open.

Figs. 3 and 4 are fragmentary elevational views of the cylinder showing the gap guard closed and opened respectively.-

Figs, 5 and 6 are Views corresponding to Figs. 1 and 2 illustrating a slight modification. y

Referring to the drawings, there is illustrated a conventional form of printing cylinder having a prinitng sector 1 and a balancing sector 8, each supported by Webs 9 from a hub IU which is adapted to be secured on a rotary shaft of a printing machine. Gaps II extend longitudinally of the cylinder between end discs, one of which is shown at I2. Integral with or secured to the end disc I2 is a gear wheel I 4'which provides a means of. rotating the cylinder by meshing with suitable gearing on the machine. in printing cylinders of this type, the gaps II inside of the guard plate and springs into lockl ing position to hold the guard ofpen when the edge of the guard plate clears the detent. Mounted on a convenient part 28 of the machine, at a lpoint where the guard plates, on closing, are out of the reach of the operator, is a tripping element 29 which, as shown, may be in the form of a fixed cam arranged to engage the detent 26 andpress `it radially inwards suiciently to enable the guard plate I9 to close under the action of the springs 23. The outer end of the detent 26 may be i oppositely bevelled as shown so that one bevelled can cause the edge of the guard plate I9 to push As is usual s accommodate clamps I5. fitted with clamping screws I6 to enable the clamps I5 to grip the end margins Ila of a printing plate` l1 which extends around the printing sector 1. Adjusting screws I3 also enable the clamps I5 to be adjusted for fitting and removing or changing the printing plate I1, land for stretching or tightening theA printing plate upon the printing sector.

the radius of curvature of the surface of the* balancing sector 8 so that the latter will not pick up ink from the inking rollers or Contact the damping rollers with which the printingV plate I1 co-operates during the printing operation.

In order to prevent theoperators hands or iingers from being inserted in the gap II, I provide a safety guard which in the form shown comprises a vplate I9 which can be made of metal or any suitably stili material which is curved as shown to substantially follow the periphery of the cylinder. The curved edges of the segmental plate I9 are received in arcuate guides formed by channels 20 providing arcuate grooves at the ends of the cylinder. The channels 20 or their outer webs may be removably secured by screws 2I (Figs. 3 and 4) 4to enable the guard plate I9 to be detached for repairs. Finger holes or recesses 22 (Figs. 3 and 4) inthe plates I9 enable them to be moved in the channels 20 vto open the guards when the cylinder is stationary.

As shown in Figs. 1 to 4, each guard plate I9 is attached on its insideto springs 23 anchored to the interior of the cylinder in such a position that the springs tend to close the guards. Attached to each end disc I2 of theI cylinder is a bracket 24 which slidably receivesthe tail stem 25 of a radially movable detent 26 urged out- Wards by a spring 21. IThe detent 26 is located in such a ,position as to engage the free edge of the guard plate I9 when the latter is open as shown at the right-hand side of Fig. 1 and in Figs. 2 and 4. When the guard plate I9 is closed or nearly closed, the detent 26 bears against the the detent further inwards after the iixed cam 29 has initially pressed the detent inwards, the

guard plate I9 iinally riding over the detent 26 and being closed to cover the gap in the cylinder by the pull of the closing springs `23.r One edge of each guard plate I9 abuts, when the guard plate is closed, against the inturned marginal edge Ila of the printing plate, and the other edge of the guard plate I9 overlaps the dead sector 8 of the cylinder, and the surface of the guard plate I9 is at al1 times suiiiciently below the surface of revolution of the `printing plate to be' clear of the inking and dampingrollers or other elements which co-operate with the cylinder. The closing springs 23 may be anchored at one end to lugs 30 on the inside of the guard lIplate I9 and at the other end to lugs 3| on the effective sector 1, so as to obtain the maximum eiective pull on the guard plate. n v

Referring now to Figs. 5 and 6 which illustrate a slight modification, each guard plate I9 is shown articulated to telescopic radius rods 32 l,pivoted at their inner ends at 33 to brackets 34 venient part in the interior of the cylinder. The

radius rods 32 are controlled by tension springs 35 which connect the radius rods to lugs 36 at fixed points in the interior of the cylinder in such a position that the springs 35 tend to turn the radius rods about their pivots 33 in a direction to close the guard plates. This alternative arrangement may be found more convenient vwhere it is desired to give complete freedom of access to` the printing plate clamps I5 and the adjusting screws IIand I8.

I claim:

1. In combination with a rotary cylinder having the cylinder surface interrupted by a gap extending longitudinally of the cylinder, a safety guard device comprising a segmental guard, arcuate guides on the cylinder to slidably` receive the .curvedA edges of said guard for closing and open-V ing movement across the gap in the cylinder, means operative to effect closing movement of the guard, a locking device for holding the guard in openV position, and a tripping device operative to release the said .locking device automatically 0n rotation of the cylinder through less than one complete revo-lution.

2. In combination with a rotary cylinder having the cylinder surface interrupted by a gap extending longitudinally of the cylinder, a safety guard device comprising a segmental guard, arcuate guides on the cylinder to slidably lreceive the curved edges of said guard for closing and'opening movement acrossjthe gapiinf theicylinder,

means operative to effect closing movement of the guard, a locking device for holding the guard in open position, and a tripping device operative to releasethe said locking device automaticallysurface of the guard is at all times slightly nearer the centre of the cylinder than the effective contact surface ofthe cylinder.

3. In combination with a rotary printing cylinder having a printing sector, a dead sector of smaller radius than the `printing sector and separated therefrom by gaps extending 1ongitudinally of the cylinder, a safety guard device comprising a pair of segmental guards, arcuate guides on the cylinder arranged to slidably receive the curved edges of said guards for closing and opening movement across the gaps in the cylinder` and for movement over the surface ofthe dead sector, said arcuate guides being so positioned that the outer surfaces of the guards areat all ,timesA nearer the centre of the cylinder than the extending longitudinally ofthe cylinder, a safety guard device comprising a segmental plate adapted to cover the gap and of slightly smaller radius than the radius of curvature of the effective contact surface of `the cylinder, arcuate channels at the ends of said cylinder, `said channels `slidably receiving the curved edges of said plate,

spring means connecting said plate on its inside to the interio-r or the cylinder, said spring means tending to close said plate over the gap, a radiallymovable detent attached to the end of the cylinder and urged outwards by a spring, said detent being arranged to engage one edge of said plate to hold it in a position in which it uncovers the gap, and a fixed tripping element arranged to trip said detent in one position of the cylinder to enable the plate `to close under the action of the said spring means.

5. `In combination with a rotary cylinder having the cylinder surface interrupted by a gap` extending longitudinally of the cylinder, a safety guard device comprising a segmental plate adapted to cover the gap and of slightly smaller radius than the radius of curvature of the eiective contact surface of the cylinder, arcuate channels at the ends of saidcylinder, said channels slidably -receiving the curved edges of said plate, spring means connecting said plate on its inside to the interior` of the cylinder, said spring means tending to close said plate over the gap, a raf dially-movable detent attached to the end of the cylinder and urged outwards by a spring, said detent;` being arranged to engage one edge of said4 plate to hold it in a position in which it uncovers the` gap, said detent having oppositely bevelled faces at its outer end, and a fixed cam arranged to engage one of the bevelled faces of said detent to trip said detent in one position of the cylinder and to permit the edge of the guard plate to engage the other bevelled face of said detent, so that said spring means can close the plate over the gap. i

WILLIAM JAMES PIRIE. 

